People outside the WEIRD (Western, Educated, Industrialized, Rich, Democratic) populations don't experience them. They are not shaped by evolution, but likely b

People outside the WEIRD (Western, Educated, Industrialized, Rich, Democratic) populations don't experience them. They are not shaped by evolution, but likely by the excess iron in western food that gets into the brain and shifts the brain chemistry towards a psychosis like state. (you can look up studies on rats, or I can look up some if you want) People who are immune to it have Asperger's or something similar "on the spectrum". Anyway, here is one: https://www.ncbi.nlm.nih.gov/pubmed/6138953 https://www.ncbi.nlm.nih.gov/pubmed/6138953